Update

brainfuck.md

@@ -8,7 +8,7 @@ The language is based on a 1964 language P´´ which was published in a mathemat
 
 Brainfuck has seen tremendous success in the [esolang](esolang.md) community as the **lowest common denominator language**: just as mathematicians use [Turing machines](turing_machine.md) in proofs, esolang programmers use brainfuck in similar ways -- many esolangs just compile to brainfuck or use brainfuck in proofs of [Turing completeness](turing_complete.md) etc. This is thanks to brainfuck being an actual, implemented and working language reflecting real computers, not just a highly abstract mathematical model with many different variants. For example if one wants to encode a program as an integer number, we can simply take the binary representation of the program's brainfuck implementation.
 
-In [LRS](lrs.md) program brainfuck may be seriously used as a super simple [scripting language](script.md).
+In [LRS](lrs.md) programs brainfuck may be seriously used as a super simple [scripting language](script.md).
 
 ## Specification
 
@@ -23,10 +23,70 @@ A program consists of these possible commands:
 - `>`: move the data pointer to the right
 - `<`: move the data pointer to the left
 - `[`: jump after corresponding `]` if value under data pointer is zero
-- `]`: jump after corresponding `[` if value under data pointer is zero
+- `]`: jump after corresponding `[` if value under data pointer is not zero
 - `.`: output value under data pointer as an ASCII character
 - `,`: read value and store it to the cell under data pointer
 
-## Variations
+## Implementation
+
+This is a very simple [C](c.md) implementation of brainfuck:
+
+```
+#include <stdio.h>
+
+#define CELLS 30000
+
+const char program[] = ",[.-]"; // your program here
+
+int main(void)
+{
+  char tape[CELLS];
+  unsigned int cell = 0;
+  const char *i = program;
+  int bDir, bCount;
+  
+  while (*i != 0)
+  {
+    switch (*i)
+    {
+      case '>': cell++; break;
+      case '<': cell--; break;
+      case '+': tape[cell]++; break;
+      case '-': tape[cell]--; break;
+      case '.': putchar(tape[cell]); fflush(stdout); break;
+      case ',': scanf("%c",tape + cell); break;
+      case '[':
+      case ']':
+        if ((tape[cell] == 0) == (*i == ']'))
+          break;
+
+        bDir = (*i == '[') ? 1 : -1;
+        bCount = 0;
+          
+        while (1)
+        {
+          if (*i == '[')
+            bCount += bDir;
+          else if (*i == ']')
+            bCount -= bDir;
+          
+          if (bCount == 0)
+            break;
+          
+          i += bDir;
+        }
+        
+        break;
+      
+      default: break;
+    }
+    
+    i++;
+  }
+}
+
+```
+
+## Variants
 
 TODO